This application claims priority from a provisional application filed Jul. 1, 1997, under U.S. patent application Ser. No. 60/051,419, entitled xe2x80x9cAir Pad.xe2x80x9d This invention relates to an air pad and in particular to an air pad that automatically spreads an impinging force over a larger area of a surface, reducing the force per unit area sufficiently to protect the surface from damage and/or to provide improved comfort.
Various types and structures of air pads are known. Many are difficult to produce on a large scale and at a low enough cost to be widely accepted in the marketplace. The present invention has been developed to provide an air pad which can be economically produced on a commercial scale and provide improved performance compared to previous air pads.
The air pad of the present invention includes first and second plastic film portions that are joined to one another forming two or more air chambers with integral, interconnecting air passages therebetween. Both the air chambers and the air passages contain foam.
The plastic film portions can be joined together by a heat joining process such as dielectric welding or sealing, also known as radio frequency welding, as well as a variety of other plastic heat joining processes including, but not limited to, ultrasonic welding, vibration welding, induction welding, microwave welding, friction welding, etc. In addition, adhesive bonding of the plastic sheets can be used in some embodiments of the air pad.
In one method of manufacturing the air pad, a layer of sheet foam is placed between the two plastic film portions. The plastic film portions are joined by radio frequency welding. During the joining process, the plastic film portions, in the areas surrounding the air chambers, are fused together to join the film portions. Additionally, where the plastic film portions are joined, the cellular structure of the foam layer between the plastic film portions is collapsed. The collapsed foam material forms a part of the fused joint between the plastic film portions.
In another method of manufacturing the air pad, a foam body is pre-molded or pre-formed in the shape of the air chambers and interconnecting air passages. The plastic film portions may also be pre-molded into the shape of the air chambers and interconnecting air passages. The plastic sheets are then joined together with the pre-molded foam body therebetween, substantially filling the air chambers and air passages.
The air pad is preferably manufactured as a sealed air tight pad. If desired, an inflation valve, or pump, to inflate the air pad, such as that shown in U.S. Pat. No. 4,566,137, hereby incorporated by reference, can be added to the air pad to enable the air pressure within the pad to be varied.
The air pad of the present invention can be used to provide impact protection for various parts of the body. When an impact is received, air will flow from one or more of the chambers, through the interconnecting air passages, to adjacent chambers in response to an increased air pressure within the chambers receiving the impact. The foam, within both the air chambers and the interconnecting air passages, slows the flow of air between chambers. This regulation or restriction of the air flow from one chamber to the next, prevents the air chambers from deflating as quickly as air chambers in a pad with no restriction of the air flow between chambers.
The air pad can be used to provide impact protection within protective equipment such as that worn during athletic events. This includes shin guards, knee pads, elbow pads, shoulder pads, within a flexible fabric or elastic cover, etc. The air pad can also be used to provide impact protection as a pad within a substantially rigid shell such as a helmet, shoulder pad, elbow pad, etc. The air pad can also be used in low or no impact applications where additional cushioning is desired for comfort, as opposed to impact protection. These uses include, but are not limited to, shoulder straps and handles for luggage, briefcases, computer cases, golf bags, back packs, etc. The air pads can also be used in shoes, shoe tongues, etc.
Since the air pad is made by placing a foam sheet between two layers of plastic and then fusing the plastic together between the desired air chambers, it is simple to manufacture the pad. As a result, economical manufacture on a commercial basis is possible. A wide variety of sizes and shapes can be made. Different performance characteristics, i.e., impact spreading and cushioning can be achieved by different foam thicknesses and types of foam.